Police lead the 34-year-old man from a Martin Place office. Photo: Police Media

The solicitor is expected to appear in court on Friday morning where he will also face charges of resisting arrest and possessing a prohibited weapon.

Police allege undercover officers bought 500 millilitres of gamma-hydroxybutyrate (GHB), or "fantasy", and 13.8 grams of methylamphetamine, or "ice", from the man on a number of occasions between late July and mid-August this year.

Investigators say he was in possession of three grams of ice, an ice pipe, scales, numerous resealable plastic bags, and a large amount of cash when they arrested him on Thursday.

They also searched his Newtown home, in Sydney's inner west, where they allege they found a stun gun and 700 millilitres of a liquid thought to be GHB.

As part of the same investigation, police searched a Kings Cross unit where they say they found 40 grams of cocaine, 10 grams of ice, 350 MDMA capsules, 10 grams of ecstasy and a large amount of cash.

At the unit, they arrested a 25-year-old man from Macquarie Park and later charged him with supplying a prohibited drug, among other charges.